1. Field of the Invention
This invention relates to electronic materials useful in the field of various electronic devices and more particularly, to electronic elements having a film of a perovskite compound whose crystallographic axes are oriented. The invention also relates to a method for making the oriented film. The term "oriented film" used herein is intended to mean a film of a crystalline material whose crystallographic axes are oriented in certain directions.
2. Description of the Prior Art
In recent years, many studies have been extensively made on thin films of perovskite compounds. Typical devices or elements using these thin films are pyroelectric heat detecting elements using PbTiO.sub.3 films, optical modulation elements using PLZT (lead lanthanum zircono-titanate) thin films, and capacitor elements using BaTiO.sub.3 thin films. For obtaining good electric or electronic characteristics, these thin film elements should be arranged in such a way that the crystallographic axes of the thin film are oriented in given directions. To this end, it is the usual practice to provide a single crystal such as MgO as a substrate and subject a perovskite compound to epitaxial growth on the substrate. Although the thin film of the perovskite compound formed on the single crystal substrate such as, for example, by sputtering exhibits a good orientation tendency, it is necessary to provide an electrode between the MgO single crystal substrate and the thin film for detection of signals when the thin films is applied as a pyroelectric heat detector element or device. This is disadvantageous in that the orientation tendency of the perovskite compund such as PbTiO.sub.3 lowers. In addition, the single crystal substrate is very expensive.